Grouting natural stone

Doing a small border as a backsplash in a bathroom. The tile is 1"x1" pieces of travertine amd marble on mesh, I'm going to cut it into 4" strips and then use a travertine chair rail to finish the top. Do I seal all the tile before I put it up or after it is glued up and before grouting? I have read the natural tiles must be sealed before grouting so the grout doesn't bleed into the tile or stain it. Also, how do I keep the grout from filling the holes in the travertine pieces? Or is there a way to get the grout out afterwards?

You could also use Grout Release. I use one made by Aqua Mix. You put it on to seal the stone tiles before grouting..Makes a HUGE difference. You might still need haze remover, but not likely if you're quick. I tried the grout bag and gave up. I have 18x1.5 ft of 1/2" stone and glass mosaic tile..I would be filling grout lines for a year if I used a grout bag.